Only One Explanation
by Bernini
Summary: Phineas, Ferb, Isabella and the rest of the Flynn-Fletcher family spend a night at Grandma and Grandpa Flynn's cabin. When a storm rolls in and Isabella gets scared will Phineas finally realize his feelings?
1. Chapter 1

_A/N: Disclaimer- I don't own Phineas and Ferb_

Only One Explanation 

It was the first day of summer vacation and Phineas, Ferb, Isabella and the rest of the Flynn-Fletcher Family were spending the weekend at Grandma and Grandpa Flynn's cabin. Buford and Baljeet were already at the first bully-nerd convention of the summer.

As soon as the car came to a stop Phineas, Ferb and Isabella jumped out and started unloading the trunk. However, before they could touch anything Candace interrupted them.

"If you even think about ruining my vacation I will bust you. Jeremy is hiking somewhere in these woods and I don't want you to ruin any chance I have of running into him."

"Don't worry Candace, we're not planning anything big. We're just going to set up our tent," Phineas replied.

"That's it? That's all you're planning?" Candace asked incredulously. "In that case just keep on working. But don't plan anything else because I will bust you." With that Candace walked away.

Phineas turned to his brother. "Ferb, did you pack the tent?" he asked.

Ferb nodded as he pulled a small cube out of the trunk.

"Wow, mad packing skills," Phineas noted. "Did you get the one with the hot tub and the waterslide?"

Once again Ferb nodded.

"Perfect," Phineas said as a huge smile spread across his face. "Ferb, why don't you go find the hose to fill up the hot tub while me and Isabella set up the tent."

Ferb blinked and walked away.

Phineas and Isabella turned to the small cube Ferb had given to Phineas and started to unfold it.

Suddenly a flash of light shot across the sky and the ground shook from the loud noise it created.

"What was that noise?" Candace yelled, sticking her head out of a second story window.

"That wasn't us," Phineas yelled back. "It was thunder and lightning from that storm that's rolling in over the mountains." As if to help prove his point another bolt of lightning struck, shaking the ground again with another loud rumble.

"Well keep it down," Candace yelled before pulling her head in and slamming the window shut.

Just then, the clouds broke open and let out the moisture they were holding. The kids quickly ran for the shelter of the cabin, but were unable to make it without getting drenched. The three of them stood on the porch, soaking wet, watching the storm. Both Phineas and Ferb enjoyed watching storms but Phineas could tell that Isabella didn't. Although she was barely moving Phineas could tell that Isabella jumped every time lightning struck. Was it possible that the leader of the Fireside Girls, who everyone thought was fearless, was scared of a thunderstorm?

Suddenly, Phineas felt the need to protect Isabella, although why he felt the need to protect her completely escaped him. He brushed off the strange thoughts and suggested, "Why don't we go inside and change into some dry clothes. We can set our sleeping bags up in the living room and camp out there tonight."

Five minutes later Phineas, Ferb and Isabella sat in the living room, patiently waiting for the storm to pass. Phineas and Ferb sat at the window looking out at the storm, their minds whirling as it inspired new inventions the boys could build this summer. Ferb was trying to think of a way to harness the electricity created by the lightning and store it for long term use. Phineas was trying to think of a way to control the weather so they could go back to their campout. He also wanted to be able to control the storm in order to help calm Isabella's fears. Out of the corner of his eye he could see her sitting on the floor clearly trying to distract herself from the storm. She was attempting to carry on a conversation as usual but with each lightning strike her jumps became more pronounced. Phineas decided that he had to do something to help her. Just as he stood up to go comfort her, a bolt of lightning struck the power lines and the house was plunged into darkness. Isabella screamed and Phineas was immediately at her side. He sat down next to her and instinctively pulled her into a hug.

"Isabella," Phineas whispered in her ear. "Everything's fine. The storm just knocked the power out, I'm sure it will be back on any minute."

Suddenly, the room was flooded with light, not from the electrical lights above them, but from the glowing fireplace in front of them. They could see the outline of Grandpa Flynn as he crouched in front of the fireplace, building up the fire until it illuminated the entire room.

Phineas realized he was still holding Isabella and hurriedly let go before anyone could notice. As he moved he felt a pang in his chest, almost as if he regretted having to let her go. He brushed it off adding it to the list of things to think about later, as the rest of the family wandered into the living room.

Linda and Lawrence fumbled blindly down the dark stairs, running into the walls and each other as Candace ran past them. Ferb stayed at the window continuing to enjoy the storm while Phineas and Isabella moved closer to the fire. Although Phineas no longer had his arm around her they stayed close together. Isabella was still scared of the storm and Phineas still felt a strange need to protect her. He considered putting his arm around her again, but was worried about what his family would think. He knew his parents and grandparents would say something embarrassing that he could easily brush off. Ferb would remain silent but would give Phineas a significant look that only Phineas would understand. However, he was pretty sure that Candace would completely freak out. Being the hopeless romantic that she is her mind would immediately jump to the conclusion that Phineas had a crush on Isabella, and Phineas had no idea how to deal with Candace's response.

Just then, Grandma Flynn came into the room carrying a big pot and placed it on the fire, interrupting Phineas' thoughts. "The soup should be done in a half hour. Phineas, Ferb why don't you two go find some candles to help light the room while the rest of us work on making dinner," she said as she handed them a couple of flashlights.

Phineas and Ferb agreed and stood up to begin their search of the house. Before Phineas left the room he glanced back at Isabella and saw her jump as another bolt of lightning lit up the sky. Phineas felt the urge to run back to her, but resisted when he heard his brother searching in the kitchen.

By the time Phineas and Ferb had found enough candles, dinner was ready. Phineas resumed his seat next to Isabella while Ferb lit the candles and set them around the room. The gang ate their soup in relative silence until someone knocked on the door.

"I wonder who that could be," Grandpa Flynn said as he made his way to the front door. The group remained silent as they listened to the mumbling coming from the door.

The silence ended when Grandpa Flynn led the mysterious visitor in the room and Candace yelled, "Jeremy! What are you doing here? I thought you were camping."

"I was," Jeremy replied. "But we got separated by the storm. Coltrane has the tent so I came in search of shelter."

"Well, you're more than welcome to stay here," Grandma Flynn said.

"You can use our room," Phineas added. "Me and Ferb and Isabella we're planning on camping out in the living room."

"Thanks guys," Jeremy said as he sat down next to Candace.

A couple hours later the group was still gathered around the fire, enjoying some sticky s'mores. As they devoured the chocolate, marshmallows and graham crackers the conversation turned to Grandpa Flynn's favorite subject, scary stories. Grandpa Flynn was a master story teller and soon all of the children were shaking in fear. Ferb had moved closer to the light and warmth of the fire. Candace had scooted closer to Jeremy and had buried her head in his shoulder while he wrapped his arm around her. Suddenly, Phineas was highly aware of how close Isabella was. Her knee was inches from his own and he found that if he moved ever so slightly their legs would touch and he would feel a tingling sensation from where her skin touched his. Isabella's close proximity also drew attention to the fact that she still jumped at every lightning strike. Phineas didn't understand why he was so concerned that Isabella was frightened by the storm, or why he felt the need to protect and comfort her. Phineas became so engrossed in trying to figure out his predicament that he didn't realize that Grandpa Flynn had finished his story until the adults stood up to go to bed.

"Don't stay up too late," Grandma Flynn said. "Even if it's still raining we have big plans for tomorrow."

As the adults filed out of the room Phineas, Ferb and Isabella started to lay out their sleeping bags and prepare for bed. Jeremy and Candace were still cuddling in front of the fire, conversing in low whispers. A while later they went off to their separate bedrooms, Jeremy giving Candace a tender kiss on the lips before turning in.

Ferb had set up his sleeping bag next to the fire and was already nestled deep in the folds of the fabric. Phineas was about to crawl into the sleeping bag he had laid out next to his brother when he turned to look at Isabella. He could tell by the way she was moving that she was still scared.

Wondering why such a small thing could scare one of the bravest people he knew Phineas asked, "What's wrong Isabella? You seem scared."

"It's nothing," she replied. "I just have a silly, irrational fear of thunderstorms." She sat down on the couch and looked over at Phineas. "When I was in kindergarten I was a munchkin in a production of the Wizard of Oz. All of the munchkins had to hide somewhere on stage during the part with the tornado. I was chosen to hide inside Dorothy's spinning house. While I was inside the spinning house I developed a very strong fear of tornadoes that has expanded to include all types of storms." Isabella looked down at her hands in embarrassment. "It's silly that a fake storm in a musical that I was in years ago still freaks me out but…"

"It's not silly," Phineas said as he sat down next to her. "Until my mom married Ferb's dad and I started sharing a room with Ferb I was terrified of the dark. I would sleep with a night light and would still end up sneaking into my mom's room because I was so scared. Sometimes I still get scared and have to turn my lamp on."

They fell silent as another loud rumble shook the house. Isabella stiffened at the terrifying sound. As Phineas sensed Isabella's fear he finally gave in to the urge to protect her and wrapped his arms around her, pulling her into another hug.

"Thanks Phineas," she mumbled into his shoulder. "You always know how to make things better."

"It's not a problem," Phineas replied.

Not wanting Phineas to leave Isabella said, "Do you think you could stay just a bit longer?"

"Of course," Phineas replied, grateful for an excuse to continue to comfort her.

Phineas pulled a blanket onto their laps as Isabella snuggled up next to him, leaning her head on his shoulder and wrapping her arms around his middle.

Phineas, at first, was surprised by Isabella's actions, but he quickly overcame it as he realized how much he enjoyed holding her.

They sat in silence, content with being in each other's arms. Phineas' thoughts turned to the events of the day. He thought of all those times he wanted to protect and comfort her today; when the storm started, when the power went out, and when he had to leave her to find the candles. He remembered his attempt at a plan to control the weather, based mainly on his desire to help her. He also recalled the regret he felt when he let go of her after Grandpa Flynn had started the fire. After that he had felt an unquenchable hunger to hold her again, and now that he was he never wanted to let go.

Suddenly, he remembered Jeremy and Candace right before they went to bed, how he had pulled her close and had given her a gentle kiss. Phineas pictured himself and Isabella in their shoes.

Phineas shook his head, clearing his mind of the image. He couldn't kiss Isabella, only people in love kissed, and he was not in love with her. They were just really good friends. Sure, he really enjoyed when Isabella came over to work on their daily projects and he was always disappointed when she had plans with the Fireside Girls and he didn't get to see her. But he felt that way with his other friends too, but not to the same extent. In fact, at times he was glad when Buford and Baljeet weren't around. Buford's bullying got annoying fast and Phineas hated how Baljeet always tried to steal Isabella's attention. It occurred to Phineas that he was actually jealous of the attention she gave Baljeet.

Phineas glanced over at Isabella and was suddenly struck with how beautiful she was. The light from the candles reflected off her raven black hair and her cheeks had a slight pink tint. Although her eyes were closed Phineas recalled the soft blue color of her gentle eyes.

Try as hard as he could, Phineas could think of only one explanation. The reason he felt the need to comfort and protect Isabella, the reason he felt so jealous, and the reason he found her so strikingly beautiful was simple, he was in love with her. The more he thought about it, the more sense it made.

He was suddenly very worried about how Isabella would react to his realization. Would she be grossed out and stop hanging out with him? He thought back on the events of the past year and it suddenly occurred to him that she could possibly feel the same way about him. Maybe the reason she was always so eager to participate in their daily activities was because she wanted to be close to him. Not to mention, Isabella had voluntarily turned to Phineas for comfort and had eagerly snuggled up next to him.

After giving it quite a lot of thought Phineas came to the conclusion that she liked him too. There was just too much evidence to think otherwise. The only question that remained was what he should do about it. Once again his mind returned to Candace and Jeremy earlier that night and the kiss they shared. Phineas felt that kissing Isabella was the proper thing to do, he just didn't know when. Should he kiss her now, before he lost his courage or should he wait for a more opportune time? Deciding that now would be the best time he took a deep breath to prepare himself. But when Phineas glanced down at Isabella he found that she had fallen asleep. Not wanting to wake her up he settled with giving her a light kiss on the temple. The real kiss would just have to wait until tomorrow. Phineas leaned his head against Isabella's and soon joined her in a peaceful sleep.

When Ferb woke up the next morning he was surprised to find Phineas and Isabella still wrapped in each other's arms, even though the storm had died down several hours ago.


	2. Chapter 2

_A/N: I had a couple requests for a second chapter so here it is. I don't own Phineas and Ferb_

"Do you want to tell us where we are going Grandpa?" Phineas asked as he hiked up a mountain with his Grandparents, his siblings, Ferb and Candace, and his newfound love Isabella.

"I'm afraid I can't Phineas," Grandpa Flynn replied. "I don't want to ruin the surprise."

"How much longer is it going to be?" Candace asked, clearly exasperated at having to come on the hike. She was at the back of the group, her feet dragging as she attempted to keep up.

"We're about halfway there," Grandma Flynn replied. "We can stop and take a break if you need to."

Candace fell face down in the grass, "Thank goodness," she mumbled.

"I'm going to go fill up my water bottle," Isabella said as she pulled her water filter out of her bag and headed to the stream near the path. Phineas watched her skip down to the little creek, a small smile dancing across his face. It was only last night that Phineas discovered that he liked Isabella, but when he thought about it he knew that he had liked her from the day they had met. Phineas now longed to tell Isabella how he felt.

"Why haven't you told her yet?" Ferb asked quietly.

"What are you… I don't know… Is it that obvious?" Phineas sputtered. Ferb just nodded. "Well," Phineas said trying to think of an answer to his brother. "I guess I haven't told her because I don't know how to. I can't just walk up to her and say 'Isabella I love you' without building up to it somehow."

Candace's head shot up from where she had fallen in exhaustion. "Did you just say you loved Isabella?"

Phineas blushed and nodded. Candace squealed. "That is so cute." Standing up she continued, "but you're right. You can't just tell her. You have to sweep her off her feet first."

"How do I do that?" Phineas asked innocently.

"It's obvious," Candace replied. "You have to show her you love her before you can tell her. Be her knight in shining amour."

Phineas had no idea how he was supposed to do that and was about to ask Candace to explain further when Isabella returned from the stream.

"Hey guys, whatcha' talkin' about?"

"Nothing," Phineas said quickly, his hand absentmindedly shooting up to scratch his ear.

"Are you guys ready to keep going?" Grandpa Flynn said, walking up to the group of kids.

"Sure thing Grandpa," Phineas said. Candace just moaned.

"What's the matter Candace?" Isabella asked.

"I hate hiking," she replied.

"You seemed pretty eager to come when Jeremy was still here," Grandpa Flynn teased.

"Well yeah," Candace said. "I don't want him thinking I'm lame."

"He doesn't think you're lame honey," Grandma Flynn said reassuringly. "You saw how much he wanted to come but he had to get back to his campout with Coltrane."

Candace continued to talk about Jeremy, allowing Phineas to zone out and try to come up with a way to become Isabella's knight in shining armor. He thought back to his history class last year. His teacher had said that knights were defenders of the weak and the helpless. But Isabella was neither weak nor helpless. Her job as leader of the Fireside Girls Troop had taught her how to take care of herself and her friends. Phineas supposed, though, that everybody had their weaknesses. Last night's thunderstorm proved it. However, he couldn't think of any other weaknesses. He would just have to keep an eye out and be ready to jump to her rescue.

Phineas supposed that if a chivalrous knight and a beautiful maiden were hiking through the mountains the knight would offer to help her on the treacherous journey, even if she didn't need any help. He glanced over at Isabella to see if there was any way he could help her, and saw her stumble over some rocks. He reached out and grabbed her arm to prevent her from falling.

"Thanks Phineas," Isabella said.

"That's what I'm here for," he replied. Out of the corner of his eye he could see Candace and Ferb watching them. They both had knowing grins spread across their faces. Candace was pointing at her hand, clearly mouthing 'hold her hand.'

Phineas smiled at his siblings' antics, laughing at how eager they were for him to kiss Isabella. Phineas decided to take Candace's advice, despite her craziness. He slid his hand down Isabella's arm and entwined his fingers in hers.

Isabella glanced over at Phineas, smiling shyly. Although she was ecstatic that he was holding her hand, she couldn't help but question his behavior. It was so unlike him to show any sort of affection, he was usually so oblivious to anything remotely romantic. In fact, last night was the first time he had intentionally done anything romantic. Isabella wanted to believe that Phineas liked her as much as she liked him, but she was afraid of getting her hopes up too high.

Phineas and Isabella continued to hike hand in hand up the mountain. Every once in a while Isabella would stubble again, but Phineas was always there to steady her. Even when they stopped to give Candace a break (which happened a lot) Phineas didn't let go of Isabella's hand.

It was on one of these breaks that Candace asked, "Are we there yet?"

"Almost, it's just around that bend," Grandma Flynn replied pointing up the path. Candace breathed a sigh of relief.

The group walked up the last couple of feet. When they reached the last bend in the path they could hear a thunderous roar of water on water. They hurried around the bend and saw a beautiful waterfall cascading into a crystal clear lake. Cliffs ranging in size from a couple of feet to over thirty feet high surrounded the whole lake.

Phineas walked over to the nearest edge, glancing down the few feet to the water's surface. His clear view to the bottom of the lake was interrupted by schools of rainbow colored fish. He leaned over the edge, trying to get a better view of the bottom and lost his balance, tumbling headfirst into the water.

Isabella gasped and ran over to the edge of the lake. "Are you ok Phineas?" she called out.

"I'm fine," he replied, shaking the water out of his eyes.

"Do you need any help?" she asked, offering Phineas her hand.

"Thanks Isabella, but the water is really nice. You should join me," Phineas said as he took Isabella's outstretched hand and pulled her into the water. She let out a small scream as she fell, pushing Phineas under the water again. They both came up gasping for breath.

"Phineas!" Isabella grumbled.

"Sorry, I couldn't help it, " he replied, swimming closer to her.

"Oh, you're going to be sorry," she said with a mischievous glint in her eye. She launched herself at Phineas, trying to dunk him, but Phineas was ready for her. When she put her hands on his chest to push him under wrapped his arms around her waist and pulled her down with him. When they finally surfaced Phineas still had his arms around Isabella, their faces were inches apart. Phineas glanced down at Isabella's lips, his heart speeding up when he realized how close they were. If he leaned in just a bit further their lips would touch.

Suddenly off in the distance he heard his Grandpa yell, "Cannon ball!" There was a huge splash and an enormous wave washed over the two kids. Phineas let out a sigh of frustration as he let go of Isabella. His grandpa had always had the knack for ruining a moment.

Soon the rest of the group had joined them in the water. As they played Phineas tried to think of a way to show Isabella his feelings. He wanted to make her something special but he had left his tools back at the cabin so his options were rather limited. Phineas looked around him for inspiration. He noticed a path that meandered around the lake and disappeared behind the waterfall. He thought that the secluded area would be perfect if he could somehow ditch the rest of the group.

He was about to ask Ferb to create a distraction when Grandma Flynn called out, "Who's ready for lunch?"

"Me!" Everyone replied in unison as they swam to the shore. Soon they were all settled on a big blanket in the shade of an old tree. Grandma Flynn passed around the sandwiches she had packed. The group ate their food quickly, surprised at how hungry they were. By the time Grandma Flynn pulled a full cake out of her bag no one could keep their eyes open. They were so tired that they didn't question Grandma Flynn for bringing a cake. Grandma and Grandpa Flynn were asleep before they could take a bite of their cake. Ferb and Candace were soon to follow. Isabella was fighting hard to keep her eyes open. Phineas alone seemed to have enough energy to stay awake. He glanced over at Isabella and was suddenly struck by her beauty. Her long black hair was starting to dry and the ends were beginning to frizz. Her eyes sparkled with the bright sunlight. Despite her sleepiness a small smile lit up her face.

Phineas realized that now was the perfect time to tell Isabella how he felt. He leaned over to Isabella and said, "Do you want to go for a walk?"

"I would love to," she said rubbing the tiredness from her eyes.

They both jumped to their feet and set off down the trail.

"This is a really beautiful place," Isabella commented.

"I know," Phineas agreed. "I can't believe my grandparents haven't brought us up here before. It's such a cool place. We can go swimming and fishing and cliff jumping and I think this path goes behind the waterfall. I bet there are tons of caves back there. We can go spelunking."

"I've always wanted to go spelunking," Isabella said.

"Perfect!" Phineas said. He grabbed Isabella's hand and speed off down the path. They reached the waterfall in no time and were unsurprised to find a cavernous cave hidden behind it. Phineas looked around the cave and noticed a narrow ledge near the ceiling. He pointed up at it and said, "Let's climb up there."

Isabella agreed and led the way to the ledge. When she reached the cave wall she started the short climb to the top.

"Be careful Phineas," she said. "It's pretty slippery up here." As soon as the words left her mouth her feet lost their traction and she fell off the cave wall, her ankle hitting a protruding rock on the way down. Luckily, Phineas was standing beneath her and managed to catch her before she hit the ground.

Once again Phineas found himself within inches of Isabella, and this time there was nothing to stop him. Before he knew it he had smashed his lips onto Isabella's. When he finally pulled away, Isabella was too shocked to react. She was stunned that Phineas had actually kissed her. Phineas took her shocked silence as rejection. He turned bright red and started mumbling. "I'm sorry…"

"Don't be," Isabella interrupted him.

"Good," he said with a smile, "because I love you."

Isabella smiled, "I love you too."

Phineas leaned in for another kiss. Isabella responded with such enthusiasm that she almost knocked Phineas off his feet. Finally, after a much longer and much more passionate kiss, they broke apart.

Phineas gently set Isabella down but the second her foot touched the ground she winced in pain.

"What's wrong?" Phineas asked worriedly.

"It's my ankle," Isabella replied. "I think it might be broken."

"Do you think you can put any weight on it?" He said as he gently felt the brake.

Isabella shook her head, "It's pretty bad. I have a splint in my bag that might help but I left it back by the lake."

Phineas gently picked her up again. "In that case, I'll carry you," he said with a smile.

They fell silent as Phineas walked down the trail. Phineas was concentrating hard on not jostling Isabella too much. He already felt guilty for suggesting they go spelunking and getting her injured, he didn't want to hurt her anymore. Isabella was trying hard not to wince whenever her foot moved. Finally they reached the blanket and found that the rest of the family had woken up.

He set Isabella delicately down onto the blanket and said, "I think she broke her ankle."

"What on earth were you doing?" Candace asked.

"We went spelunking, you know cave exploring." Phineas explained. "We were climbing up one of the walls and Isabella slipped. I caught her before she hit the ground but she hit her ankle on the way down."

Grandma Flynn was now examining Isabella's ankle. "Could you tell it was broken right after it happened or did it take a while before you noticed it?"

Isabella blushed. "Well, I was a little distracted right after so I'm not sure."

"It's not that important." Grandma Flynn said. "But if you don't mind my asking, what were you doing that could distract you from the pain of a broken ankle?"

Isabella glanced at Phineas, as deep red blushes spread across both of their faces.

"We, um, we were," Phineas tried to explain. "We kissed." Everyone reacted just as Phineas predicted.

"Well it's about time," Grandpa Flynn said. "I though you would never figure it out. I was planning on locking you two in a closet until you figured it out."

"Grandpa!" Phineas said, clearly embarrassed. He looked over at his brother, hoping he would diffuse some of the embarrassment, but Ferb just sat there with a smug look on his face, clearly happy that Phineas had overcome his obliviousness.

Candace, meanwhile, was freaking out. "I can't believe you guys finally got together. I need to call Jeremy and Stacy and Mom and Dad. It's just so exciting."

"Oh honey I almost forgot in all the excitement, we need to wrap you ankle before we head back down the mountain," Grandma Flynn said as she took the brace out of Isabella's bag. She wrapped Isabella's ankle as carefully as she could but Isabella still whimpered in pain every time her foot was moved. Phineas knelt by her side holding her hand and comforting her. Grandma Flynn quickly finished, "That should hold you over until we can get you to a hospital. Do you think you can walk on it?"

"I'm not sure," Isabella said. Phineas helped her to her feet. She slowly placed her foot on the ground and took a step. She held back a cry as pain shot through her leg. "I think I'll be fine," she fibbed. She took a couple more uneasy steps to prove she could make it. Phineas, however, wasn't fooled. He could clearly see that she was in a lot of pain.

"Don't be silly Isabella. Your ankle looks pretty bad, you probably shouldn't be putting any weight on it," Phineas said.

"Then how is she going to get back to the cabin?" Candace asked.

"I'll carry her," Phineas answered simply. Isabella smiled gratefully as Phineas swept her up in his arms.

They began the long trip back down the mountain. Every once in a while Isabella's broken ankle would brush up against a stray branch or Phineas' side and she would wince in pain. Every time Phineas would profusely apologize and give her a swift kiss on the cheek. Isabella would smile and return the favor. Although she was in more pain that she would like to admit she was comforted by the knowledge that Phineas had finally realized his love for her.


End file.
